Thermo-Physical Properties of SiCAl Composites with High Volume Fraction of Reinforcement Prepared by Combining Powder Injection Molding and Pressure Infiltration

Abstract

SiC/Al composites with high reinforcement content were fabricated by pressure infiltration of aluminum alloy into porous SiC preform obtained by powder injection molding using a bimodal powder mixture. The influence of powder loading and particle size on the thermo-physical properties of the prepared composites was investigated. The results indicate that the thermal conductivities (TC) increases and coefficients of thermal expansion (CTE) decreases with increasing powder loading and particle size of the coarse powders in the bimodal powder system. The TCs are below the estimated value based on Hasselman-Johnson model, mainly due to the residual pores and the irregular particle shape. The CTEs of the composites increase with increasing temperature from 100°C to 400°C, and the increasing rates vary at different temperature ranges. Deep cooling in liquid nitrogen is effective to bring dislocations in the matrix and thus reduces the CTEs.